The present invention relates to the field of ophthalmology. More specifically, the invention is directed to compositions and methods for disinfecting contact lenses, and to the preservation of various types of pharmaceutical compositions, particularly ophthalmic, otic and nasal pharmaceutical compositions and compositions for treating contact lenses.
Contact lenses are exposed to a broad spectrum of microbes during normal wear and become soiled relatively quickly. Routine cleaning and disinfecting of the lenses are therefore required. Although the frequency of cleaning and disinfecting may vary somewhat among different types of lenses and lens care regimens, daily cleaning and disinfecting is normally required. Failure to clean and disinfect the lens properly can lead to a multitude of problems ranging from mere discomfort when the lenses are being worn to serious ocular infections. Ocular infections caused by particularly virulent microbes, such as Pseudomonas aeruginosa, can lead to loss of the infected eye(s) if left untreated, or if allowed to reach an advanced stage before treatment is initiated. It is therefore extremely important that patients disinfect their contact lenses in accordance with the regimen prescribed by their optometrist or ophthalmologist.
Unfortunately, patients frequently fail to follow the prescribed regimens. Many patients find regimens to be difficult to understand and/or complicated, and as a result do not comply with one or more aspects of the regimen. Other patients may have a negative experience with the regimen, such as ocular discomfort attributable to the disinfecting agent, and as a result do not routinely disinfect their lenses or otherwise stray from the prescribed regimen. In either case, the risk of ocular infections is exacerbated.
The use of amidoamines, quaternary ammonium compounds, and biguanides as disinfecting agents is well known. The following U.S. patents may be referenced for further background regarding the use of such compounds in the ophthalmic field: U.S. Pat. No. 5,631,005; U.S. Pat. No. 4,525,346; and U.S. Pat. No. 4,537,746.
The inclusion of long chain alkyl groups in amidoamine and quaternary ammonium compounds generally increases the antimicrobial activity of these compounds. However, as the chain length is increased, the solubility of the compounds in water decreases. The reduction in solubility negates the improved antimicrobial activity resulting from the increased chain length.
Solubility and associated antimicrobial activity may be further affected by buffered solutions, such as those typically used in contact lens disinfection. There is, therefore, a need for a means of enhancing the activity of antimicrobial agents by increasing alkyl chain length without reducing the solubility of the agents.